Electrolyte and composition for forming the same



Patented Nov. 11, 1924.

PATENT OFFICE.

' AUGUST HEGK, OF PHILADELPHIA, PENNSYLVANIA ELECTROLYTE AND COMPOSITION F03 FORMING THE SAME.

No Drawing.

To all whom it may concern:

Be it known that I, AUGUST zen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Electrolytes and Compositions forForming the Same, of which the following is a specification.

My invention relates to electrolytes, and compositions for forming the same, used in the electro-deposition of metals such as copper, zinc, brass, silver and gold.

Heretofore, in the art of electroplating,

one of the most common forms of electro-' lytes or plating solutions consisted of asolution of cyanide of the metal to be deposited and cyanide of sodium or potassium. to which were sometimes added carbonate of soda, ammonium chloride, or other so-called conducting salts, the essential ingredients I of the electrolyte being the cyanides, and

the other materials being added in various quantities for the purpose of improving the conductivity of the electrolyte according to various formulae employed.

It frequently occurs, however, that, in the use of the cyanide solutions, either with or without the addition of the conductlng salts, the electrolyte will break down or decompose, resulting in the formation and deposition of scum or slime, and in some instances resulting in the precipitation of the useful materials, which renders the electrolyte solution unfit for use.

The object of my resent invention is to provide an improve and a prepared composition for use by the electro-plater in making the same, which electrolyte will be more stable and durable than the various cyanide solutions at present in common use, and will better maintain its eflicien'cy in use.

The nature and characteristic features of my invention will be more readily understood from the following description of the improved form of electrolyte and the pre-. ferred form of the composition for preparing the same:

- The general practice of preparing cyanide electrolytes consists in first dissolving a suitable quantity of cyanide of sodium or pometal to be deposited, For example, for

Hnou, a citi-' form of electrolyte, 4

Application filed August 22, 1923. serial in. 658,670.

copper plating, copper cyanide is used; for

z1nc plating, zinc cyanide is used;'for brass plating, a mixture of copper and zinc cyanidcs in the proper proportions is'used; for silver plating, silver cyanide is used; and for gold plating, gold cyanide is used. After the solution is prepared, there. are sometimes added suitable quantities of conducting salts, such as carbonate of soda, sal' ammoniac, bisulphite of soda, etc., for the purpose of increasing the conductivity of the solution. r

Numerous formulae have been evolved for the preparation of cyanide solutions, but it is found in the practical use of the same that frequently, after the solution has been permitted to stand fora short time, the same will break down and decompose, the metals quent expense and loss of time.

I'have found that, in the use of cyanide solutions, by .the addition of a suitable quantity of boracic acid, the breaking down of the electrolyte will be largely eliminated, the same rendered more stable, the metal will be deposited more uniformly and in a heavier deposit in a given time, and the use of the so-called conducting salts may be dispensed with.

For the purpose of making up the electro-- lyte, it will be found advisable to mix the boracic acid with the particular cyanide of the metal in a dry form, and furnish the same to the electro-plater so mixed together. In making up this composition, there is preferably used about 50 parts of the boracic acid to each 100 parts of the metal cyanide;

When the electro-plater desires to make. up the bath, a suitable quantity of the prepared composition is used, which is mixed with the water in which the-cyanide of sodium, or potassium, has previously been dissolved. While various strengths of the solution may be used, according to the conditions under which the electro-plate'r is ac- .customed to work, the following formulae cyanide, 6 ounces; prepared copper composition (copper cyanide and boracic acid) 12 ounces.

For zinc: Water, 1 gallon; sodium cyanide, 8 ounces; prepared zinc c0mposit= (zinc cyanide and boracic acid) 12 ounces.

For brassz-Water, 1 allon; sodium cyanide, 8 ounces; prepared copper composition (copper cyanide and boracic acid) 8 ounces; grepared zinc composition (zinc cyanide and oracic acid). 6 ounces.

For silver: Water, 1 gallon; sodiumcyanide, 6 ounces; prepared silver composition (silver cyanide and boracic acid) 8.0unces.

For gold: Water, 1 gallon; sodium cyanide, 3 ounces; prepared gold composition (gold cyanide and boracic acid) 2 ounces.

By the employment of the prepared compositions for making up the electrol tes according to the above or any'other desired formulae, the solutions may subsequently be brought to proper balance whenever it may be found necessary to replenish any of the materials which. may have been used up. For example, if it should be found that, after use for a certain period, the electrolyte contains an excess off'ree cyanide of sodium, the same can be brought to proper balance by the addition of a suitable quantity of-the prepared composition; or, if the electrolyte be found too rich in metal, it can be brought to a balance by the addition of' a suitablequantity of cyanide of sodium, or potassium, as the case may be.

It will be found thatyby the use of the electrolytes prepared as hereinbefore described, the stability and lasting qualities of the same will be greatly enhanced, the metal will be more uniformly and firmly deposited, and the electro-plating will be greatly improved generally.

When it will be found that in the use of electrolytes prepared as hereinbefore set forth, the addition of conducting salts,

such as carbonate of sode, sal ammoniac,

"baths for use in nickel plating, but so -far as I am aware, the same has not heretofore been employed in the preparation of alkaline electrolytes" in which cyanides of the. metals to be deposited and cyanides of sodium, or M potassium, are the prmcipal active ingredients.

Having thus described the nature and characteristic features of my present invention, what I claim as new. and desire to secure by Letters Patent isi" 1. An electrolyte for, use in electro-deposition of metalsconsisting ofa solution" in water ofan appreciable amount of cyanide of an alkali metal, together with a mixtureof solutions of cyanide of the met;

al to be deposited, and boracic acid, the I latter ingredients being present in relatively large amounts.

2. An electrolyte for use in electrodeposition of metals consisting of a solution in water of an appreciable quantity of cyanide of an alkali metal and approximately doublethe quantity of a mixture of cyanide of the metal to be deposited and boracic metal to be deposited, and a relatively large proportion of boracic acid.

4. A composition for use in preparing cyanide solutions for electro-plating purposes, consisting of cyanide of the metal to be deposited, and boracic acid, the boracic acid being approximately one-half the quantity of the cyanide of the metal. I

5. The improvement in the art of electroplating which consists in the employment in an electrolyte of the cyanide typeof a quantity of boracic acid in a relatively large proportion. I

6. The improvement in the art of electroplating which consists in the employment in an electrolyte of'the cyanide ty e of boracic acid in approximately one-ha f the amount of the cyanide of the metal.

In testimony whereof, I have hereunto signed my name.

AUGUST 'HEOK.

acid, in-the approximate proportions of 

